Digital Signal Processing Algorithm And Circiut Research On LVDT Displacement Sensor

Along with electro-hydraulic servo control technology development, the eletro-hydraulic servo value is widely applied in industrial field. Practice has proved that that it can improve the frequency response and control precision of the eletro-hydraulic servo value by the use of spool displacement sensor to form a closed loop system. LVDT, as one of the most widely used eletro-hydraulic servo value spool displacement sensors, its displacement detection accuracy has a direct effect on the eletro-hydraulic servo values closed-loop performance. Therefore, LVDT and its signal processing methods are the hot topic of current research. This paper mainly builds up a2D model and carries on the detail electromagnetic field simulation and analysis in the Ansoft Maxwell. Meanwhile, this paper demonstrates a digital signal processing methods of LVDT according to the problem such as the temperature drift, large power consumption, difficulties in nonlinear correction in traditional LVDT analog signal processing methods, and advanced research on digital signal processing methods of LVDT and some related experiment has been done.The first chapter first briefly introduces the development of both eletro-hydraulic servo control technology and the electro-hydraulic servo valve spool displacement detection technology development status, and then introduces the research status of LVDT and its signal processing methods at home and abroad. Finally, put forward the goal of this topic and content in view of the shortcomings of the current research.The second chapter makes a deep analysis of LVDT theoretical basis. Firstly, the most commonly used LVDT-three section type LVDT’s working principle is presented in detail, and then establish its equivalent circuit, in which we can get the electrical characteristics relationship, and the relationship between the incentive frequency responce and output is analyzed. Secondly, establishes the mathematical model of the three section type LVDT according to the electromagnetic field knowledge, and get the mathematical expression between its structure parameters and the output.The third chapter is mainly about LVDT modeling and simulation. It has established a2D LVDT model with a coil of simplified model in the electromagnetic field simulation software Ansoft Maxwell in the light of the structure characteristics of LVDT, and both the static magnetic field and transient field simulation is carried out. The static magnetic field simulation is on study of the magnetic field distribution and the changing rule of mutual inductance between the LVDT two subprime coils and primary coil. Transient field simulation is on study of the influence on the LVDT output characteristic of eddy current, voltage source incentive frequency, current source incentive frequency and coil circle number, following some experiment has done to make comparison.The fourth chapter is about research on digital signal processing algorithm of LVDT. The existence of the amplifier circuit of the sine incentive signal has higher power consumption, and difficulty in stablizing its amplitude and frequency under high frequency, so that a square wave signal as excitation signal method is introduced. At the same time, the current LVDT digital signal processing algorithm are compared, and the sine wave amplitude three valuations method is on the further research of analysis. Finally, the LVDT temperature compensation method and the nonlinear correction method are discussed, and present the methods base on software to realize both temperature compensation method and nonlinear correction method.A LVDT digital signal processing circuit board was made based on the study of the algorithm introduce above to test algorithm in the fifth chapter. The static test and dynamic test was carried on with the LVDT digital signal processing circuit board. The static test is research on temperature compensation algorithm, in which verify the temperature compensation method is correct but has limitations, and verify the correctness of the nonlinear correction method of LVDT. Dynamic test is on the influence of the incentive LVDT frequency on the dynamic response characteristics by the LVDT signal processing circuit board, and that the relevant conclusions are got.The sixth chapter comprehensively summaries the completed work and points out problem to be solved in this research, proposed the following research focus.